Donkey Kong Country Returns (Wii)

Cranky's gift
On the game select screen, choose a file that has fewer than 4 balloons, and Cranky will increase your lives total to 4.
Temple stages
Collect all the K-O-N-G letters in each stage of a world to unlock that world's temple stage.
Golden Temple
Beat the boss in World 8 to unlock the ninth world: Golden Temple.
Mirror Mode
To unlock Mirror Mode, beat the Golden Temple. In Mirror Mode, the levels are mirrored, you only have one heart, and you can't use Diddy or any items.